Correct the incorrect function name and description.

Fixes: a76edc89 ("pinctrl: core: Add generic pinctrl functions for managing groups")
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>